This invention relates to a microelectronic package comprising a flexible substrate and a frame affixed to the substrate to facilitate installation directly onto a support structure.
A microelectronic assembly comprises electronic components and metallic circuit traces disposed on a substrate. In most applications, the substrate is a rigid planar board. Alternately, the substrate may be a flexible polymeric film. One advantage of a flexible substrate is that it may be formed to a non-planar shape. Another advantage is that the substrate may be folded to reduce the footprint in the product. To facilitate manufacture, the substrate is maintained with a planar surface during processing to define the metal traces and attach the electronic components. After the electronic components are-mounted on one surface, the obverse surface is attached to a carrier to prevent damage to the components and the electrical connections which might otherwise occur due to flexing of the substrate during handling and installation into the product. In addition, the carrier is typically formed of metal to serve as a heat sink to extract heat generated by the electronic components and thereby maintain a lower operating temperature for the assembly.
The carrier adds to the size, weight and cost of the assembly. In many applications, the assembly Is then mounted onto a support structure within the product. For example, the assembly may be mounted onto an installation site that is part of the chassis of an automotive vehicle. Under these circumstances, the support structure is able to reinforce the substrate and also to serve as a heat sink. However, access to the installation site may be limited, for example, by other components of the vehicle. Thus, the carrier has been required to allow the package to be manipulated onto the installation site and fastened without damage and within a reasonable time conducive to mass production operations.
Therefore, a need exists for a microelectronic package that comprises a flexible substrate that may be folded and shaped into a desired configuration and readily installed with the obverse surface of the substrate against a support structure in the product, without an intermediate carrier. The package needs to be accurately and quickly positioned and fastened to the support structure without damage to the electronic components or electrical connections and within a time conducive to mass production operations. Elimination of the carrier would reduce the size, weight and expense of the package and utilize the support structure in the product to provide mechanical strength and heat extraction during operation.
In a preferred embodiment, this invention provides a microelectronic package that comprises a flexible substrate that is folded and formed in a desired configuration and mounted directly onto a support structure. The flexible substrate has a first portion, a second portion and a fold therebetween. The first portion includes a first electronics-bearing surface region, a first perimeter about the first surface region and an obverse surface opposite the first region. The second portion has a second electronics-bearing surface region and second perimeter about the second surface region. Electronic components are attached to the first and second surface regions and the flexible substrate is folded at the fold to arrange the second surface region to face the first surface region. In accordance with this invention, the microelectronic package includes a frame having a first side affixed to the first perimeter and a second side affixed to the second perimeter. The frame includes one or more holes adapted to receive fasteners for mounting the microelectronic package onto the support structure. It is a feature of this invention that the frame is affixed to the first perimeter of the first portion, so that the obverse surface is free to be mounted directly against the support structure. The frame reinforces the flexible substrate and forms the microelectronic package into a desired configuration to facilitate handling and installation without damage to the electronic components or electrical connections.